US account, RC case number:11046551,
Software version of Polycom VVX 250 phones: 184.108.40.20632
Plantronics Blackwire 3215, 3220, and 3225 headsets connected directly to the phone via USB.
After spending 3 hours on the phone with RingCentral support, (who tried as hard as they could and had engineers from Polycom/Plantronics headset and phone division on the line) we eventually failed in our goal of having our Plantronics Blackwire 3000 series headsets volume persist between phone calls on any of our phones.
After reading information on other posts it looked like the problem may have been a configuration setting with the headset parameter
If 0, the headset receive volume will automatically reset to a nominal level after each call.
Above is the default
If 1, the volume for each call will be the same as the previous call.
This exactly defines our problem and on other RC community pages changing this parameter to "1" solved the problem for other Polycom VVX phones 400, 500, and 600 series phones.
To try and view/change these settings, you find the IP address of the phone and https://<IP of phone>
From there you can log in as a user with no password but for admin, you have to get the password from RingCentral. When RC provisions the phone they change the default "456" password to something else and apparently it is different per phone and it's not a simple 3 digit code. The RC rep was good enough to give me the admin password for one of the phones, and when I downloaded the config file, I was disappointed to see that all of the voice.volume.persist parameters were already set to "1". So that was basically the end of it. I even tried setting it back to "0" myself and uploading the config. But rebooting the phone looks like it just pulls the config from RC again and overwrites any changes. So RC central command seems to be the best place to make these changes anyway and they already have.
But the story goes on and the case is still open. The firmware on the phones (5.8.2) is a version supported by RC. Polycom has point versions all the way up to 6.3. The unsuspecting Polycom rep wanted us to upgrade the firmware with no guarantee that it would solve the problem. But the RC rep was quick to shut him down and set my expectations that upgrading the firmware would remove any RC features. So I get that RC has a supported firmware they like to use. But I hope that one day RC may issue a new firmware for the VVX 250 and that it may address the headset persistent problem.
Another longshot is the Polycom rep gave me a link to the VVX 250 5.8.0 Administrator Guide
And on this particular page is a parameter
0 (default) The USB headset volume does not persist between calls and is reset each new call.
1 - The USB headset volume at the end of a call persists between calls.
This "USB" parameter doesn't exist in our current VVX 250 config but the 5.8.0 Administrator guide shows that it's an option. A "site" option, which sounds like something that RC could provision for me (and all VVX 250 users) and not something that I could change on the phone.
So I'm hoping a friendly RingCentral engineer will stumble upon this post with an "I can fix it" attitude and drop that parameter into our config to see if that changes something or chooses a 6.x firmware release to test the persistent headset volume and if so rollout it out to the entire RC community so all of us VVX 250 users can rejoice!